Diode laser arrays have a most prominent advantage of high electrical-to-optical efficiency and so are very suitable for use in industrial processing. But their defect is poor beam quality which affects their range of industrial applications.
Prior techniques for improving the beam quality generally fall into two categories, coherent superposition and non-coherent superposition. Coherent superposition is essentially the superposition of the amplitudes of the light waves. While it can effectively improve the output beam quality of the semiconductor arrays, coherent superposition requires the phases of the various superposed sub-light-sources be synchronously locked, which entails high technical difficulty, making it hard to obtain high-power in-phase stable output. Non-coherent superposition is the superposition of luminous intensities, including methods such as beam shaping, superposition of polarizations, or superposition of wavelengths. Existing luminous intensity superposition techniques, however, are difficult to obtain ultra-high brightness beams, and the beam quality improvement is limited. Most of these techniques are passive ones which can only passively improve the total beam quality through beam shaping under existing array parameters.